1. Field of the Invention
The present invention relates to a driving circuit for driving multiple light emitting elements.
2. Description of the Related Art
Battery-driven electronic apparatuses such as cellular phones, PDAs (Personal Digital Assistants), etc., mount a device which requires higher voltage than the output voltage of a battery, such as an LED (Light Emitting Diode) employed as a backlight for a liquid crystal panel, etc. For example, in many cases, such an electronic apparatus employs a lithium ion battery which supplies an output voltage of around 3.5 V in the normal state, and an output voltage of around 4.2 V even in the fully charged state. However, a higher voltage than the battery voltage is required as the driving voltage for the LED. In a case in which such a higher voltage than the battery voltage is required, the battery voltage is boosted using a switching regulator or a charge pump circuit so as to obtain the voltage necessary for driving a load circuit such as LED etc. The related art is disclosed in Patent document 1.
[Patent Document 1]
Japanese Patent Application Laid Open No. 2005-260110
In the circuit described in Patent document 1, of the LEDs for the three colors R, G, and B, the LEDs for G and B are driven using the boosted voltage, and the LEDs for R are driven using the voltage which is switched between the battery voltage and the boosted voltage.